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Published on: November 20, 2017
Plant COP9 signalosome subunit 5, CSN5
Dan Jin1, Bosheng Li2, Xing-Wang Deng2
1Key Laboratory of Biotechnology and Crop Quality Improvement of Ministry of Agriculture, Biotechnology Research Center, Southwest University, Chongqing 400716, China; Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA.
Abstract:
CSN5 is a subunit of the COP9 signalosome (CSN) and carries the metallo-protease catalytic center for the complex. This highly conserved gene has been a subject of intense research in part because human Csn5 (Jab1) has been tightly linked to cancer. We briefly summarize recent research advances on the structure and mechanisms of the CSN in general, and then focus on the Arabidopsis CSN5 genes and their products, AtCSN5A and AtCSN5B. We also briefly discuss CSN6 genes, which are closely related share many similarities to CSN5. CSN5 and CSN6 genes are duplicated in mustard family of plants as well as in several plant species that have no phylogenetic correlation. Sequence homology comparison further suggests that at least some of the duplication events occurred independently. We review and analyze the phenotypic and expression differences of the two CSN5 genes in Arabidopsis, and suggest that they play overlapping as well as specialized roles in plant development. Arabidopsis CSN5 protein sequences are more similar to those of complex organisms such as humans than to yeasts and unicellular alga, suggesting that the structure and mechanism of Arabidopsis CSN5 likely resembles more to those of human than to yeast. We argue that possession of two different isoforms of CSN5s gives Arabidopsis a unique advantage as a genetic model of CSN5 to dissect the multifaceted functions and mechanistic versatilities of this important cellular regulator.
Insights
The COP9 signalosome subunit CSN5, crucial in cellular regulation and linked to cancer, has duplicated genes (AtCSN5A and AtCSN5B) in Arabidopsis. These genes exhibit distinct roles in plant development, offering a model for studying CSN5 functions.
Area of Science:
- Plant molecular biology
- Cellular regulation
- Genetics
Background:
- CSN5 is a key subunit of the COP9 signalosome (CSN), possessing metallo-protease activity.
- The human homolog of CSN5 (Jab1) is implicated in cancer, driving research into its conserved functions.
- CSN5 and related CSN6 genes have undergone independent duplications in various plant lineages.
Purpose of the Study:
- To investigate the structure, mechanisms, and functional divergence of Arabidopsis CSN5 genes (AtCSN5A and AtCSN5B).
- To analyze phenotypic and expression differences between AtCSN5A and AtCSN5B.
- To establish Arabidopsis as a model system for dissecting the multifaceted roles of CSN5.
Main Methods:
- Comparative sequence homology analysis of CSN5 and CSN6 genes across plant species.
- Review and analysis of existing phenotypic and gene expression data for Arabidopsis CSN5 isoforms.
- Comparison of Arabidopsis CSN5 protein sequences with homologs in diverse organisms.
Main Results:
- Arabidopsis possesses two distinct CSN5 genes, AtCSN5A and AtCSN5B, resulting from independent duplication events.
- Phenotypic and expression analyses suggest overlapping and specialized roles for AtCSN5A and AtCSN5B in plant development.
- Arabidopsis CSN5 proteins show higher sequence similarity to human CSN5 than to yeast or algal homologs.
Conclusions:
- The duplicated CSN5 genes in Arabidopsis likely fulfill both shared and unique functions in plant growth and development.
- Arabidopsis serves as a valuable genetic model for understanding the complex functions and mechanisms of CSN5 due to its distinct isoforms.
- The conserved nature of CSN5 across eukaryotes highlights its fundamental importance in cellular regulation.
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